From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Petr Mladek <pmladek@suse.com>,
Steven Rostedt <rostedt@goodmis.org>,
Alexander Potapenko <glider@google.com>,
Dmitriy Vyukov <dvyukov@google.com>,
kbuild test robot <fengguang.wu@intel.com>,
syzkaller <syzkaller@googlegroups.com>,
LKML <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] printk: inject caller information into the body of message
Date: Fri, 28 Sep 2018 18:09:39 +0900 [thread overview]
Message-ID: <20180928090939.GE1160@jagdpanzerIV> (raw)
In-Reply-To: <7dadfa8c-1f69-ae0f-d747-dbbc9f97c2b6@i-love.sakura.ne.jp>
On (09/24/18 17:11), Tetsuo Handa wrote:
> The reason of using statically preallocated global buffers is that I think
> that it is inconvenient for KERN_CONT users to calculate necessary bytes
> only for avoiding message truncation. The pr_line might be passed to deep
> into the callchain and adjusting buffer size whenever the content's possible
> max length changes is as much painful as changing printk() to accept only
> one "const char *" argument. Even if we guarantee that any context can
> allocate buffer from kernel stack, we cannot guarantee that many concurrent
> printk() won't trigger lockup. Thus, I think that trying to allocate from
> finite static buffers with a fallback to unbuffered printk() upon failure
> is sufficient.
Yes, this makes sense. At the same time we can keep pr_line buffer
in .bss
static char buffer[1024];
static DEFINE_PR_LINE_BUF(..., buffer);
just like you have already mentioned. But that's going to require a
case-by-case handling; so a big list of printk buffers is a simpler
option. Fallback, tho, can be painful. On a system with 1024 CPUs can
one have more than 16 concurrent cont printks? If the answer is yes,
then we are looking at the same broken cont output as before.
-ss
next prev parent reply other threads:[~2018-09-28 9:09 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <201804232233.CIC65675.OJSOMFQOFFHVtL@I-love.SAKURA.ne.jp>
[not found] ` <CACT4Y+boyw_Qy=y-iTnsKZrtTgF0Hk3nHN_xtqUdX4etgiYDQw@mail.gmail.com>
2018-04-24 1:33 ` printk feature for syzbot? Sergey Senozhatsky
2018-04-24 14:40 ` Steven Rostedt
2018-04-26 10:06 ` Petr Mladek
2018-05-10 4:22 ` Sergey Senozhatsky
2018-05-10 11:30 ` Petr Mladek
2018-05-10 12:11 ` Sergey Senozhatsky
2018-05-10 14:22 ` Steven Rostedt
2018-05-10 14:50 ` Tetsuo Handa
2018-05-11 1:45 ` Sergey Senozhatsky
[not found] ` <201805110238.w4B2cIGH079602@www262.sakura.ne.jp>
2018-05-11 6:21 ` Sergey Senozhatsky
2018-05-11 9:17 ` Dmitry Vyukov
2018-05-11 9:50 ` Sergey Senozhatsky
2018-05-11 11:58 ` [PATCH] printk: inject caller information into the body of message Tetsuo Handa
2018-05-17 11:21 ` Sergey Senozhatsky
2018-05-17 11:52 ` Sergey Senozhatsky
2018-05-18 12:15 ` Petr Mladek
2018-05-18 12:25 ` Dmitry Vyukov
2018-05-18 12:54 ` Petr Mladek
2018-05-18 13:08 ` Dmitry Vyukov
2018-05-24 2:21 ` Sergey Senozhatsky
2018-05-23 10:19 ` Tetsuo Handa
2018-05-24 2:14 ` Sergey Senozhatsky
2018-05-26 6:36 ` Dmitry Vyukov
2018-06-20 5:44 ` Dmitry Vyukov
2018-06-20 8:31 ` Sergey Senozhatsky
2018-06-20 8:45 ` Dmitry Vyukov
2018-06-20 9:06 ` Sergey Senozhatsky
2018-06-20 9:18 ` Sergey Senozhatsky
2018-06-20 9:31 ` Dmitry Vyukov
2018-06-20 11:07 ` Sergey Senozhatsky
2018-06-20 11:32 ` Dmitry Vyukov
2018-06-20 13:06 ` Sergey Senozhatsky
2018-06-22 13:06 ` Tetsuo Handa
2018-06-25 1:41 ` Sergey Senozhatsky
2018-06-25 9:36 ` Dmitry Vyukov
2018-06-27 10:29 ` Tetsuo Handa
2018-09-10 11:20 ` Alexander Potapenko
2018-09-12 6:53 ` Sergey Senozhatsky
2018-09-12 16:05 ` Steven Rostedt
2018-09-13 7:12 ` Sergey Senozhatsky
2018-09-13 12:26 ` Petr Mladek
2018-09-13 14:28 ` Sergey Senozhatsky
2018-09-14 1:22 ` Steven Rostedt
2018-09-14 2:15 ` Sergey Senozhatsky
2018-09-14 6:57 ` Sergey Senozhatsky
2018-09-14 10:37 ` Tetsuo Handa
2018-09-14 11:50 ` Sergey Senozhatsky
2018-09-14 12:03 ` Tetsuo Handa
2018-09-14 12:22 ` Sergey Senozhatsky
2018-09-19 11:02 ` Tetsuo Handa
2018-09-24 8:11 ` Tetsuo Handa
2018-09-27 16:10 ` Tetsuo Handa
2018-09-28 9:02 ` Sergey Senozhatsky
2018-09-28 9:09 ` Sergey Senozhatsky [this message]
2018-09-28 11:01 ` Tetsuo Handa
2018-09-29 10:51 ` Sergey Senozhatsky
2018-09-29 11:15 ` Tetsuo Handa
2018-10-01 2:37 ` Sergey Senozhatsky
2018-10-01 2:58 ` Sergey Senozhatsky
2018-10-01 11:21 ` Tetsuo Handa
2018-10-02 6:38 ` Sergey Senozhatsky
2018-10-08 10:31 ` Tetsuo Handa
2018-10-08 16:03 ` Petr Mladek
2018-10-08 20:48 ` Tetsuo Handa
2018-10-09 14:52 ` Petr Mladek
2018-10-09 21:19 ` Tetsuo Handa
2018-10-10 10:14 ` Tetsuo Handa
2018-10-11 10:20 ` Tetsuo Handa
2018-10-11 13:47 ` Steven Rostedt
2018-10-08 15:43 ` Petr Mladek
2018-09-28 8:56 ` Sergey Senozhatsky
2018-09-28 11:21 ` Tetsuo Handa
2018-09-29 11:13 ` Sergey Senozhatsky
2018-09-29 11:39 ` Tetsuo Handa
2018-10-01 5:52 ` Sergey Senozhatsky
2018-10-01 8:37 ` Sergey Senozhatsky
2018-10-01 18:06 ` Steven Rostedt
2018-09-14 1:12 ` Steven Rostedt
2018-09-14 1:55 ` Sergey Senozhatsky
2018-06-21 8:29 ` Sergey Senozhatsky
2018-06-20 9:30 ` Dmitry Vyukov
2018-06-20 11:19 ` Sergey Senozhatsky
2018-06-20 11:25 ` Dmitry Vyukov
2018-06-20 11:37 ` Fengguang Wu
2018-06-20 12:31 ` Dmitry Vyukov
2018-06-20 12:41 ` Fengguang Wu
2018-06-20 12:45 ` Dmitry Vyukov
2018-06-20 12:48 ` Fengguang Wu
2018-05-11 13:37 ` printk feature for syzbot? Steven Rostedt
2018-05-15 5:20 ` Sergey Senozhatsky
2018-05-15 14:39 ` Steven Rostedt
2018-05-11 11:02 ` [PATCH] printk: fix possible reuse of va_list variable Tetsuo Handa
2018-05-11 11:27 ` Sergey Senozhatsky
2018-05-17 11:57 ` Petr Mladek
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